170 Notices of Memoirs — W. F. Kirhy — Fossil Drarjoi-Flies. 



drawn with a rounded and not an angular or even perpendicular 

 edge to the umbilicus as it should be. To judge from the figure, it 

 would be a d liferent form. 



As to G. Aalense. If specimens with different-sized umbilicus, 

 different character of ribbing, and different shape of inner edge, are 

 all varieties of one species, and no indication given of what is the 

 common feature that binds them all together, something further in 

 the way of "proof" does seem possible. 



G. siihqnadratnm versus G. Scemanni. No two specimens of Am- 

 monite are probably identical, but these seem to me (and that is all 

 I say) to be so alike, even in the matter of coiling, after measure- 

 ment, that no sensible differences can be appreciated from the 

 figures. 



On the question of the keel on the cast of a hollow-keeled 

 Ammonite I am clearly in the wrong. I was certainly not aware 

 that so well-marked a one could co-exist with a hollow keel above 

 it, till Mr. Buckman was kind enough to send me a specimen in 

 which the fact is indubitable. 



3. Mr. Lydekker says that a superficial knowledge of the subject 

 would enable any one to gauge the value of my criticisms. 1 do 

 not think myself that it requires even a superficial knowledge to 

 appreciate them, merely some common sense. It certainly never 

 struck me that OrtliojjJetirosaunis was meant for a simple rectification 

 of Orthocosta, in spite of the somewhat superfluous remark that the 

 latter is hybrid. The proper rectification, following the author's 

 guidance of '^ foJydens'' changed to '' mtdtidens" would be Recticosta. 

 We are not told whether this is objected to, or whether it and 

 Orthopleurus are preoccupied, nor is any reason given why -saurns 

 is added on, so that even now no reason is given for the actual result 

 of the change. 



4. Dr. Callaway has ordered pistols for two and coffee for one. 

 But he scarcely expects me, I think, to accept his challenge. I have 

 nothing to gain by doing so, if victorious. The fact is, I am so 

 thoroughly convinced of my own power of making a mistake, even 

 when it seems most obvious that I cannot have done so, that I never 

 come to a conclusion of my own, much less propound one for the 

 acceptance of others, till it rests on so many foundations that I feel 

 sure they cannot all be wrong; the advantage of which is that I 

 can afford to give away a few, if contested, witliout the conclusion 

 being much damaged. I do not by any means give awny the obser- 

 vations in question ; but if Dr. Callaway likes to take them, it is not 

 worth while to run after him. 



nsrOTIOES OIF- nVCIEIMIOIK/S 



T. — Fossil Dragon-Flies. 



IN the following work — A Synonymic Catalogue of Neiiroptera 

 odonata or Dragon-flies, by W. F. Kirby, F.L.S , etc., Svo. 

 Gurney & Jackson, London, IbUO — is an Appendix (pages 165- 

 176) enumerating all the known Fossil Odonata, with authorities, 



